How many plants per 100 square feet?
At 12 inch spacing, 100 square feet takes 100 plants in a square grid or 115 staggered. At 18 inches it is 44 square or 51 staggered; at 24 inches, 25 square or 28 staggered.
The staggered figure is always 1.1547 times the square-grid figure — that ratio is 2/√3 and it does not change with spacing. Each plant sits in the gap between two in the row behind, which puts the rows 0.866 of the spacing apart instead of the full spacing.
Spacing is measured centre to centre, and you should use the plant’s mature width from the label rather than the size of the pot it came in.
| Spacing | Square grid | Staggered | Row spacing |
|---|---|---|---|
| 4 in | 900 | 1039 | 3.5 in |
| 6 in | 400 | 461 | 5.2 in |
| 8 in | 225 | 259 | 6.9 in |
| 10 in | 143 | 166 | 8.7 in |
| 12 in | 100 | 115 | 10.4 in |
| 15 in | 64 | 73 | 13.0 in |
| 18 in | 44 | 51 | 15.6 in |
| 24 in | 25 | 28 | 20.8 in |
| 30 in | 16 | 18 | 26.0 in |
| 36 in | 11 | 12 | 31.2 in |
| 48 in | 6 | 7 | 41.6 in |
Using the chart
Find your spacing, take the count per 100 ft², and multiply by your bed area divided by 100. A 300 ft² bed at 18 inch staggered spacing is 51 × 3 = 153 plants.
The staggered column is 1.1547 times the square column throughout — that ratio is 2/√3 and it does not change with spacing. Every plant sits in the gap between two in the row behind, which puts the rows 0.866 of the spacing apart instead of the full spacing.
| Plant type | Spacing | Per 100 ft² staggered |
|---|---|---|
| Annual bedding plants | 6-8 in | about 461 |
| Groundcover (pachysandra, vinca) | 8-12 in | about 259 |
| Perennials, small | 12-15 in | about 115 |
| Perennials, medium | 18-24 in | about 51 |
| Hosta, daylily | 18-24 in | about 51 |
| Small shrubs | 24-36 in | about 28 |
| Medium shrubs | 36-48 in | about 12 |
| Hedge plants (informal) | 18-24 in | about 51 |
Spacing is a decision about time
Plant at the mature width and the bed looks sparse for two or three seasons, then looks right for a decade. Plant at half the mature width and it looks good in one season, then crowds.
For perennials and groundcover, planting tight and dividing later is a reasonable strategy, because dividing gives you free plants. For shrubs it is a mistake — you cannot divide a shrub, and the only remedies later are heavy pruning or removal.
Common questions
How many plants per 100 square feet at 12 inch spacing?
100 in a square grid, 115 staggered.
How many plants per 100 square feet at 18 inch spacing?
44 in a square grid, 51 staggered.
Should I measure spacing from the plant centre or the edge?
Centre to centre, always. Spacing figures on labels and in charts assume centres.